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United States Department of Agriculture

Agricultural Research Service

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Research Project: Assessment of Abiotic and Biotic Factors in Greenhouse and Field Evaluation for Fusarium Wilt (Fov) Resistance in Cotton

Location: Plant Stress and Germplasm Development Research

Project Number: 6208-21000-019-02
Project Type: Specific Cooperative Agreement

Start Date: Aug 14, 2013
End Date: Aug 13, 2016

Objective:
1. Identify environmental factors, such as temperature, inoculum level, and exposure of time (days after inoculation), that affect Fusarium wilt (FOV) pathogenicity and virulence, and disease progress to assess FOV resistance on cotton plants with different genetic backgrounds. 2. Develop and evaluate cotton progeny and breeding populations segregating for FOV resistance, yield, and fiber quality. 3. Improve or develop screening or evaluation methods for selecting breeding lines and germplasm resistant to FOV, specifically race 4.

Approach:
Selected cotton cultivars, germplasm, breeding lines and/or populations will be evaluated in infested Fusarium wilt [(FOV) Fusarium oxysporum f. sp. vasinfectum] fields and in the greenhouse using artificial FOV inoculation. Field experiments will typically use a randomized complete block or incomplete block design with 3–4 replications, or 2 replications when seed availability from selections is limited. Measured responses to FOV will include percent plant survival and the disease severity index standardized rating. The greenhouse experiments will use a completely randomized design with five replications. Each replication of an entry will be represented by one plant per pot. Roots of plants will be artificially infected with races 1 and 4 of FOV for greenhouse evaluations. We will measure the responses to FOV infection using the disease severity index of leaves and vascular root discoloration. For select cultivars advanced to broader testing: (1) yields and turnout will be evaluated based on single harvested plants, 25- or 50-boll samples, or 6-pound samples of seed cotton, depending on the amount of seed available and associated stage of progeny development; and (2) fiber quality measurements will be conducted to determine average boll size and fiber length, strength, and micronaire using HVI analyses on whole plant samples collected across a distribution of boll locations on plants. Treatment designs such as a factorial with split plot or split-split plot design will also be used to evaluate alternative approaches to test FOV responses when different levels of inoculum, different temperatures, or different days after inoculation will be included in the test. The FOV responses from these tests will be examined using ANOVA or nonparametric tests. To develop progeny and introgress Fusarium wilt [(FOV) Fusarium oxysporum f. sp. vasinfectum] resistance into breeding lines and improved germplasm, we will use traditional breeding techniques (pedigree, mass selection, single-seed descent, and backcross methods). This research will also support existing projects to identify and validate biomarkers, which will be used to incorporate genes conferring FOV resistance into elite cultivars by marker-assisted selection.

Last Modified: 7/25/2014
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